The present invention relates to agricultural sprayers of pressurized liquids and more particularly concerns such a sprayer in which liquid is agitated and in which piston leakage is contained.
Pressurized discharge of various types of liquid insecticides, fertilizers, herbicides and other agricultural-type treatment liquid has been accomplished by directly pressurizing a pressure vessel that is mounted within a portable liquid container, with a pump also connected to the container and pressure vessel. Liquid is drawn from the container, caused to flow under pressure into the pressure vessel and sprayed therefrom under control of a spraying valve.
Such sprayers need but do not provide agitation of container contents. Efficient spraying or agricultural insecticides, herbicides and the like requires control of the amount of insecticide dispensed. Manufacturers of spraying chemicals recommend preferred use rates for efficient application of the chemicals. These rates specify the amount of chemical to be used per acre. However, the recommended rates can be met only if the spraying equipment is able to control the solution strength, in addition to controlling pressure and output flow rate. For some materials, solution strength depends on the amount of nonsoluble but wettable particles maintained in suspension within the solution. In such suspensions, agitation is required to minimize precipitation of solid particles so as to maintain solution strength.
In those sprayers employing piston pumps, the life of the sprayer is often related directly to the life of the pump piston, because leakage of the liquid past a worn pump piston, must be avoided. Liquids sprayed are often toxic and leakage from the sprayer may cause severe damage to the person of the operator or other contaminatio of operator or equipment. To increase the sprayer life and minimize the leakage problem, it has been suggested, as described in my prior application identified above, Ser. No. 616,012, to replace the piston with a diaphragm pump which is not subject to the wear of the piston and which can be more readily and completely sealed for longer pump life. However, the diaphragm pump, although possessing a number of advantages, cannot provide as high an output pressure as a piston pump. Therefore, a piston pump is preferable to a diaphragm pump in many applications.
Neither practical agitation of suspensions of wettable powders nor high pressure leak proof sprayers have heretofor been available in portable agricultural sprayers.
Accordingly, it is an object of the present invention to eliminate or minimize the above-mentioned problems in the spraying of agricultural liquids.